[all-commits] [llvm/llvm-project] 78a9e6: [XCOFF] Enable -fdata-sections on AIX

[jasonliudev via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 78a9e62aa6f8f39fe8141e5486fca6db29947ecf
      https://github.com/llvm/llvm-project/commit/78a9e62aa6f8f39fe8141e5486fca6db29947ecf
  Author: jasonliu <jasonliu.development at gmail.com>
  Date:   2020-10-02 (Fri, 02 Oct 2020)

  Changed paths:
    M llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
    M llvm/lib/Target/PowerPC/PPCAsmPrinter.cpp
    A llvm/test/CodeGen/PowerPC/aix-xcoff-data-sections.ll

  Log Message:
  -----------
  [XCOFF] Enable -fdata-sections on AIX

Summary:
Some design decision worth noting about:

I've noticed a recent mailing discussing about why string literal is
not affected by -fdata-sections for ELF target:
http://lists.llvm.org/pipermail/llvm-dev/2020-September/145121.html

But on AIX, our linker could not split the mergeable string like other target.
So I think it would make more sense for us to emit separate csect for
every mergeable string in -fdata-sections mode,
as there might not be other ways for linker to do garbage collection
on unused mergeable string.

Reviewed By: daltenty, hubert.reinterpretcast

Differential Revision: https://reviews.llvm.org/D88339